This invention relates to dielectric waveguides for the transmission of electromagnetic waves wherein such waveguides comprise a dielectric core, one or more layers of dielectric cladding wrapped around the core, and one or more shielding layers wrapped around the cladding. The core and cladding preferably are polytetrafluoroethylene (PTFE), such as disclosed in U.S. Pat. No. 4,463,329. These waveguides may be fractions of an inch in diameter up to several inches in diameter. More specifically, the invention relates to a method for forming a precise joint between two sections of such a dielectric waveguide. A substantially precise joint is provided wherein the two joined sections of waveguide are precisely oriented axially, radially and rotationally with respect to each other. A technique is provided for joining two or more sections of the same dielectric waveguide with substantially no deterioration of insertion and return loss characteristics.
There are three basic reasons for being able to accurately join sections of such waveguides. A dielectric waveguide assembly may be damaged in the field due to an act of war or any other accident necessitating its repair. Second, there may be situations, particularly in cases of long assemblies, where it is not practical to feed the complete assembly from one end. In such a case, an assembly may be built and installed in suitable, shorter length sections. Third, various standard length sections with standard end couplings may be stocked so that a required length of assembly can quickly be built to meet preselected length requirements.
For a joint which has almost no insertion loss and which does not cause any appreciable reflection of electromagnetic waves, two requirements must be met. Two ends of the dielectric waveguide to be joined must be precisely cut so that they are flat and perpendicular to the axis of the dielectric waveguide to provide that, when the cut ends are brought together to form a joint, there is no air gap between them. Second, the center cores of the two sections must be in perfect angular, radial and axial alignment with respect to each other.
This invention provides a technique for producing precision joints between sections of such waveguides.